How hot did Earth get in the past? Scientists uncover new information

Jul 05, 2011

The question seems simple enough: What happens to the Earth's temperature when atmospheric carbon dioxide levels increase? The answer is elusive. However, clues are hidden in the fossil record. A new study by researchers from Syracuse and Yale universities provides a much clearer picture of the Earth's temperature approximately 50 million years ago when CO2 concentrations were higher than today. The results may shed light on what to expect in the future if CO2 levels keep rising.

The study, which for the first time compared multiple geochemical and temperature proxies to determine mean annual and seasonal temperatures, is published online in the journal Geology, the premier publication of the Geological Society of America, and is forthcoming in print Aug. 1.

SU Alumnus Caitlin Keating-Bitonti '09 is the corresponding author of the study. She conducted the research as an undergraduate student under the guidance of Linda Ivany, associate professor of earth sciences, and Scott Samson, professor of earth sciences, both in Syracuse University's College of Arts and Sciences. Early results led the team to bring in Hagit Affek, assistant professor of geology and geophysics at Yale University, and Yale Ph.D. candidate Peter Douglas for collaborative study. The National Science Foundation and the American Chemical Society funded the research.

"The early Eocene Epoch (50 million years ago) was about as warm as the Earth has been over the past 65 million years, since the extinction of the dinosaurs," Ivany says. "There were crocodiles above the Arctic Circle and palm trees in Alaska. The questions we are trying to answer are how much warmer was it at different latitudes and how can that information be used to project future temperatures based on what we know about CO2 levels?"

Previous studies have suggested that the polar regions (high-latitude areas) during the Eocene were very hotgreater than 30 degrees centigrade (86 degrees Fahrenheit). However, because the sun's rays are strongest at the Earth's equator, tropical and subtropical areas (lower latitude) will always be at least as warm as polar areas, if not hotter. Until now, temperature data for subtropical regions were limited.

The SU and Yale research team found that average Eocene water temperature along the subtropical U.S. Gulf Coast hovered around 27 degrees centigrade (80 degrees Fahrenheit), slightly cooler than earlier studies predicted. Modern temperatures in the study area average 75 degrees Fahrenheit. Additionally, the scientists discovered that, during the Eocene, temperatures in the study area did not change more than 3 to 5 degrees centigrade across seasons, whereas today, the area's seasonal temperatures fluctuate by 12 degrees centigrade. The new results indicate that the polar and sub-polar regions, while still very warm, could not have been quite as hot as previously suggested.

The findings are based on a chemical analysis of the growth rings of the shells of fossilized bivalve mollusks and on the organic materials trapped in the sediment packed inside the shells, which was conducted by Keating-Bitonti and her colleagues. Ivany collected the fossils from sediment layers exposed along the Tombigbee River in Alabama. The mollusks lived in a near-shore marine environment during a time when the sea level was higher and the ocean flooded much of southern Alabama. The sediments that accumulated there contain one of the richest and best-preserved fossil records in the country.

"Our study shows that previous estimates of temperatures during the early Eocene were likely overestimated, especially at higher latitudes near the poles," Keating-Bitonti says. "The study does not mean elevated atmospheric CO2 levels did not produce a greenhouse effectthe Earth was clearly hotter during the early Eocene. Our results support predictions that increasing levels of atmospheric CO2 will result in a warmer climate with less seasonality across the globe."

To determine the average seasonal temperatures in the study area, Keating-Bitonti sampled the mollusk shells for high-resolution oxygen and strontium isotope analyses, which were done at SU. The Yale team analyzed shells and sediments for clumped-isotope and tetraether-lipid analysis. The results were consistent across all of the independent analytic methods. The scientists believe the multiple methods of analysis have yielded a more complete and accurate picture of ancient climate than previously possible.

The study also marks the first time clumped-isotope analysis has been used alongside traditional oxygen isotope and organic geochemical analyses in paleoclimate work. The research team is currently using the same analytical process to determine Eocene Epoch mean annual and seasonal temperatures in polar-regions.

"Clumped isotopes is a new way to measure past temperatures that offers a distinct advantage over other approaches because the technique requires fewer assumptions; it's based on well understood physics," Affek says. "The agreement among different methods gives us confidence in the results and enables us to use these methods in other locations, such as Antarctica."

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lol, yeah, so why did they get it backwards? This time around is opposite of the past, so an analogy with past warming is invalid. The cause was obviously not the same, according to AGW theory. Do I really need to read the rest of this story?

The research team is currently using the same analytical process to determine Eocene Epoch mean annual and seasonal temperatures in polar-regions

If the results are consistent with the above results then it will be interesting, but the usefullness of comparing those results to current warming are extremely limited. The shape of continents and oceans was quite different then. It would take a lot of work to show how systems today might respond in the same way as the systems back then did.

lol, yeah, so why did they get it backwards? This time around is opposite of the past, so an analogy with past warming is invalid. The cause was obviously not the same, according to AGW theory. Do I really need to read the rest of this story?

The research team is currently using the same analytical process to determine Eocene Epoch mean annual and seasonal temperatures in polar-regions

If the results are consistent with the above results then it will be interesting, but the usefullness of comparing those results to current warming are extremely limited. The shape of continents and oceans was quite different then. It would take a lot of work to show how systems today might respond in the same way as the systems back then did.

Creationalists believe that 6000 years ago their god created the universe for mankind - all the galaxies and stars, the planets in our solar system, the earths geology including its myriad fossils, and the huge diversity of life.

However, using this same logic, their deity could equally have been a bit mischievous and finished creating the universe just yesterday with everything ready-made and in place including our memories, books (e.g. the biblical texts), and everything else in the universe all cunningly contrived to make it appear to have been created 6K years ago.

In fact, why stop at yesterday? Why not have creation completed just a minute ago, or just a fraction of a second ago? After all, this omnipotent god would only need to implant all the self-consistent life-memories right up to the present in everyones minds. This surely reveals the patent absurdity and the anthropocentric fallacy of having some deity create everything ready-made just a few thousand years ago!

kevinrtrs, your God created your universe less than 10,000 years ago. My God created my universe about 13.75 billion years ago, give or take a few hundred million years. Since we obviously live in different universes, this proves the theory of multiple universes. Now if we can just figure out how to return you to your universe.

It was really really really hot then as it would be now. The question you really need to ask is how long did it take to become that hot; 1 million years, 500,000 yrs, 100,000 yrs? We are doing it in 200yrs what took nature to do in 500K years. So the question to the Total AGW Republican Deniers (TARD) people is; do you think there are not consequences to such a fast CO2 level rise in the Earth's atmosphere?

I am very surprised by the determination that there was little seasonal variation in temperatures. Today, climate models are predicting higher high temperatures, and consequentially (although not able to predict yet) collapsing ecosystems. Remember the Summer of 2004 in Europe. Leemans & Eickhout predicts that if decade temperature rise is more than .6 C, then all ecosystems will be quickly destroyed, so maybe it is the temperature change that is the most reliant to runaway global warming.

The world of infinities is without measure, time, observation, or 'physicality'.

In the world of infinities, 'relationships' are the 'tools' of description. No need for 'physical' description.

For kevinrtrts, God is an infinity.There is nothing we know of that is not irreversible.(Nothing is truely 'lost' - belief in laws of conservation)We are surprise that the finite creates infinities. (People inventing Gods or the infinite.)

Sorry for the digression.Tracing past climate is tracing back infinite paths that have conditions that are the most consistent to science today.

Creationalists believe that 6000 years ago their god created the universe for mankind - all the galaxies and stars, the planets in our solar system, the earths geology including its myriad fossils, and the huge diversity of life.

No. There certainly are a few people who believe such nonsense just as there are a few people who believe the earth is flat.

Most people (including those of us who believe God created the universe) do not hold such foolish beliefs.

Accusing a large group of people of believing the foolishness of a few is disingenuous.

I did not say or imply that people who believe in Creation are few in number. I said that people who believe the nonsense that the earth is 6,000 (7,000; 10,000; etc.) years old are few. There are a few people who will believe anything -- such as the flat earth society. But there are few who believe the earth is flat and there are few people who believe the earth is a few thousand years old.

Again, it is disingenuous to label a large group of people with the nonsense of a few foolish people.

You can certainly say you do not like God. You can even say you don't believe in him (regardless of your actual belief), but calling people who believe in him idiots is childish and unproductive.

I did not say or imply that people who believe in Creation are few in number. I said that people who believe the nonsense that the earth is 6,000 (7,000; 10,000; etc.) years old are few. There are a few people who will believe anything -- such as the flat earth society. But there are few who believe the earth is flat and there are few people who believe the earth is a few thousand years old.

Again, it is disingenuous to label a large group of people with the nonsense of a few foolish people.

You can certainly say you do not like God. You can even say you don't believe in him (regardless of your actual belief), but calling people who believe in him idiots is childish and unproductive.

You shouldn't do that.

I said nothing of the sort.

As for the bulk of today's Creationists, these are Bibilical literalists, properly described as Young Earth Creationists.

As for the bulk of today's Creationists, these are Bibilical literalists, properly described as Young Earth Creationists.

Directly after saying you said nothing of the sort, you said it again.

You lie when you say that. It is just not true. Most people who believe the bible are not "Young Earth Creationists".

I, for example, believe the bible. I believe God created the universe. I do not believe in a "Young Earth".

I know many people who believe in Creation. I have never met a Young Earth Creationist and I wager you have not either. I have never met a Flat Earther either and probably never will. It is unlikely any of us will ever meet members of such a small group of foolish people.

I just want to point out the following article that highlights the actions of 'young earth creationists.' The name of the article is: "Creationism Creeps into Mainstream Geology." A geologic field trip was set up and manned by those who believe the bible literally with regard to age and "the flood." They put their own spin on the geology to gell with the bible's time frame and geologic causes for formations they refuse to believe are as old as they really are.

To interject a little sanity . . . You can go to the following site at Earth Magazine and vote on whether you would knowningly attend a field trip set up by creationists, and if not, why. There are 7 ranked responses possible.

If the Earth was hotter in the past, that would mean that a lot of it would have been flooded. That would also explain why aquatic organisms adapted to living on land as temperatures gradually cooled planet-wide and water began to freeze at the ice caps, making more land available for colonization.

This surely reveals the patent absurdity and the anthropocentric fallacy of having some deity create everything ready-made just a few thousand years ago!

Dear dear Peter, you seem to think that such a strawman makes your argument so creative. No creationist even suggests everything was ready made. That would be ludicrous, considering they would believe they were born through reproduction and obviously aren't Adam or Eve.

What a Creationist believes, whether OEC or YEC, is that God is the source of initial matter and the physical laws. Where they disagree is largely over rates and the impact of the Flood.

Now to your argument, even assuming falsely a Creationist believes that, it would be no different to believe in parallel or alternate universes. How do you know that this universe didn't just begin? Your just an offbranch/spinoff of some choice made in another universe. So the argument you make is even fruitless on this point as well and has little to do with God.

From the article: "argued that exposures of Lyon Sandstone have been misinterpreted as eolian (wind-blown). Moreover, they said, these rocks have an unusually broad geographic extent, suggesting erosion and deposition on a continental rather than local scale. Again, reading between the lines: Theyre not wind-blown deposits, theyre deposits from Noahs Flood."

That is not leaving out their religious bias. The article does indeed show, in several other comments, too, that they interpreted all the outcrops and roadcuts as showing results of flooding, even though the correct answers were not flooding.

Besides, geology has made huge strides in advancing their knowledge as a result of carbon dating and other molecular processes that have confirmed dating much older than that attributed to the 'great flood.' Read the whole story before you make comments on it. The story in physorg was only an excerpt of the complete article at:http://www.earthm...icle/456

"continental" wasn't part of the quote. It's read between the lines as much as "Noah's Flood" is.

I'm not sure how Ross can be accused either, considering he worked entirely within the current framework of standard geology for his talk.

The author here is grasping at straws. These men, despite their background, only seemed to address non religious reasons for why they believed these areas to be deluvial.

As to "wind blown" or deluvial, I don't know the areas well enough to comment. Perhaps the author could have made more comment as to why they are considered "wind blown", which is where the argument should be.

Besides, geology has made huge strides in advancing their knowledge as a result of carbon dating and other molecular processes that have confirmed dating much older than that attributed to the 'great flood.' Read the whole story before you make comments on it.

Carbon dating is based on ratio. If the ratio was largely different in the past, modern carbon dating will only be good up to that point. Same reason you can't use it based on the nuclear bomb testing era. So if there was a Flood, carbon dating is only dependable up to about 4000 years, at least until you could determine the pre-Flood ratio.

Radioactivity is concentrated in the earth's crust. Where as sedimentary layers cover over 70% of the earth's surface, it only makes up 5% of the crust. Radioactive decay rates are largely unchangeable by temp, and only very very slightly affected by pressure. However, charging a particle by stripping it's electrons will vastly increase the decay rate.

A global flood, as described in the bible, has plenty of potential energy for such chain reactions. The amount of carbaonate being dumped by subterranean water would also effect carbon dating.

For what we look at are mechanisms. One asserts long time, because the current decay rates or ratios are "normal". But just about any process or mechanism can be sped up or slowed down.

Radioactive decay rates are largely unchangeable by temp, and only very very slightly affected by pressure.

In reality, "The date of a rock is reset when volcanic activity remelts it. The date of a piece of pottery is reset by the heat of the kiln. Typically temperatures greater than 400 degrees Celsius will reset the "clock". This is termed thermoluminescence."

It is also true that depth pressure creates heat, so pressure does effect the decay clock.

I shouldn't have used carbon dating as my example. While it is true that carbon dating is not very useful in dating minerals, Wikipedia confirms what I already knew: geologists can establish the absolute age of the parent material. A number of radioactive isotopes are used for this purpose, and depending on the rate of decay, are used for dating different geological periods. More slowly decaying isotopes are useful for longer periods of time, but less accurate in absolute years. With the exception of the radiocarbon method, most of these techniques are actually based on measuring an increase in the abundance of a radiogenic isotope, which is the decay-product of the radioactive parent isotope. Two or more radiometric methods can be used in concert to achieve more robust results. Most radiometric methods are suitable for geological time only.

In my post above, the word "continental" had to be part of the quote, because I used cut and past to make sure it was exact. I don't know what article you are reading, but it's not the full article that I quoted. Here, again, is the location of the article in Earth Magazine. The quote I used is in pharagraph 13 under the heading: "Out in the Field" The full impact of the article is best when reading the full article.http://www.earthm...-7db-6-a

What a Creationist believes, whether OEC or YEC, is that God is the source of initial matter and the physical laws. Where they disagree is largely over rates and the impact of the Flood.

It is patently false to say that that is that YEC adherents believe.

They are Scriptural literalists who maintain that all happened precisely as set forth in their translations of translations of the Torah, and at precisely the speed seemingly indicated by the genealogies there set forth.

Please do not think that all here as so gullible as to simply accept your self-serving definitions.

It is surprising how much discussion goes on here about Young Earth Creationists. One might be led to believe that this is a religious site since so much time is spent arguing about a small fringe group of people.

You don't find such discussions in main stream religions because they don't care to waste time discussing irrelevancies.

However, charging a particle by stripping it's electrons will vastly increase the decay rate.

That's only been shown to hold true for certain elements under controlled circumstances, none of which are used for radiometric dating. Not all elements have the same mechanism for radioactive decay, so not all are going to be affected by changes in the electron orbitals.

A global flood, as described in the bible, has plenty of potential energy

Potential energy? Running water does not strip electrons.

...for such chain reactions.

Chain reactions? "Chain" is not a figure of speech with regards to chemical reactions. It refers to a specific subset of self-perpetuating reaction.

The amount of carbaonate being dumped by subterranean water would also effect carbon dating.

Sure, if the living organisms continued to digest after they were subjected to the flooding. Also if we were to use carbon dating for long-term geological purposes.

Typically temperatures greater than 400 degrees Celsius will reset the "clock". This is termed thermoluminescence."

Which is not a rate change though now is it? Your measuring the accumulated dose, after resetting.

For pottery it works well. Pottery is much more modern.

I don't know what article you are reading, but it's not the full article that I quoted. Here, again, is the location of the article in Earth Magazine.

I was reading from the article. The word "continental" is not included by the author in the Ross quote. It is his wording afterward. Ross could have said anything from non local, regional to continental, but we don't know.

They are Scriptural literalists who maintain that all happened precisely as set forth in their translations of translations of the Torah, and at precisely the speed seemingly indicated by the genealogies there set forth.

You just described what I said the difference is. Why would I be patently false then? I said they disagree over rates, obviously with YEC holding to the genologies/chronology/order presented.

Chain reactions? "Chain" is not a figure of speech with regards to chemical reactions. It refers to a specific subset of self-perpetuating reaction.

My apologies if misused, the point is that there were a domino of events taking place. Similar in thought to an earthquake, then causing a tsunami, then wrecking Japan. As to electricity...

Mechanical stress causes piezoelectric effect which generates plenty of electricity. Considering the subterranean, confined "running water" being tidal pumped for 1500 years, the resulting release would have made short work not only of the crust's deformation and movement, but would have generated plenty of electricity.

Cite a source please. The piezoelectric effect would not account for that sort of change across multiple types of radiometric dating methods (all of which, by the way, have been subject to a large amount of experimental scrutiny over the past 70 years that shows that environmental effects on radioactive decay are negligible).

While the forces behind a tsunami, massive flood, etc. are extremely large on the macroscopic level, I don't see how they could cause that kind of effect on an electronically stable element, nor on an element that does not exhibit electron-related decay. Just because Beryllium can be affected doesn't mean that uranium will be.

The piezoelectric effect would not account for that sort of change across multiple types of radiometric dating methods

Crust collapsing and fluttering, or compression/tension cycles that would drive the piezoelectric effect, easily generating enough electricity to break down granite. Discharging like lightning throughout the crust, the possibilities become mechanisms like z-pinch or even shock collapse. In essence the entire upper crust becomes a nuclear engine due to the build up of super critical water and the release of all that water and energy.

Note the following link, describes these conditions, based on what Biblical indications are given for prior to the Flood.

They are Scriptural literalists who maintain that all happened precisely as set forth in their translations of translations of the Torah, and at precisely the speed seemingly indicated by the genealogies there set forth.

You just described what I said the difference is. Why would I be patently false then? I said they disagree over rates, obviously with YEC holding to the genologies/chronology/order presented.